Heat transfer and pressure drop in hexagonal ducts with surface dimples

Chang, Shyy Woei; Chiang, Kuei Feng; Chou, Tsu Chien

doi:10.1016/j.expthermflusci.2010.04.006

Cited by 43 publications

(7 citation statements)

References 25 publications

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“…Geravandian et al [11] numerically simulated the laminar heat transfer of nanofluid flow in a rectangular microchannel and revealed that by increasing TiO 2 nanoparticles, heat transfer, friction coefficient, PEC, and pressure drop increase. Studies on the effect of using cooling fluid jet injection on heated surfaces [12] and other methods to increase heat transfer, such as using dimples, rough surfaces [13,14], and twisted tapes [15,16], have been conducted for different industrial and experimental geometries. These studies show that by creating vortexes, uniform temperature distribution can be obtained.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer of Oil/MWCNT Nanofluid Jet Injection Inside a Rectangular Microchannel

et al. 2019

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In the current study, laminar heat transfer and direct fluid jet injection of oil/MWCNT nanofluid were numerically investigated with a finite volume method. Both slip and no-slip boundary conditions on solid walls were used. The objective of this study was to increase the cooling performance of heated walls inside a rectangular microchannel. Reynolds numbers ranged from 10 to 50; slip coefficients were 0.0, 0.04, and 0.08; and nanoparticle volume fractions were 0-4%. The results showed that using techniques for improving heat transfer, such as fluid jet injection with low temperature and adding nanoparticles to the base fluid, allowed for good results to be obtained. By increasing jet injection, areas with eliminated boundary layers along the fluid direction spread in the domain. Dispersing solid nanoparticles in the base fluid with higher volume fractions resulted in better temperature distribution and Nusselt number. By increasing the nanoparticle volume fraction, the temperature of the heated surface penetrated to the flow centerline and the fluid temperature increased. Jet injection with higher velocity, due to its higher fluid momentum, resulted in higher Nusselt number and affected lateral areas. Fluid velocity was higher in jet areas, which diminished the effect of the boundary layer.

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Section: Introductionmentioning

confidence: 99%

Heat Transfer of Oil/MWCNT Nanofluid Jet Injection Inside a Rectangular Microchannel

et al. 2019

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“…For the thermal management of semiconductor industry, the heat flux density of electronic devices increases greatly to about 500 W/cm 2 [13]. Existing single method, such as microchannel heat transfer [14], impinging jets [15], fins [16], and dimples [17], is difficult to effectively remove the waste heat away from the chips of electronic devices with very high heat fluxes. Therefore, the combination of several technologies can be one of the solutions [18,19].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Dimples in Microchannel Heat Sink with Impinging Jets—Part B: the Influences of Dimple Height and Arrangement

Ming

Cai

Yang³

et al. 2018

J. Therm. Sci.

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The combination of a microchannel heat sink with impinging jets and dimples (MHSIJD) can effectively improve the flow and heat transfer performance on the cooling surface of electronic devices with very high heat fluxes. Based on the previous work by analysing the effect of dimple radius on the overall performance of MHSIJD, the effects of dimple height and arrangement were numerically analysed. The velocity distribution, pressure drop, and thermal performance of MHSIJD under various dimple heights and arrangements were presented. The results showed that: MHSIJD with higher dimples had better overall performance with dimple radius being fixed; creating a mismatch between the impinging hole and dimple can solve the issue caused by the drift phenomenon; the mismatch between the impinging hole and dimple did not exhibit better overall performance than a well-matched design.

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“…The secondary fl ow appears in the early stage of the development and then becomes the vortex structure. Yamamoto, Akita, Ikeuchi, & Kita, (1995) and Chang, Chiang and Chou (2010) worked in hexagonal ducts; the fi rst ones for establishing the destabilizing effect on the fl ow due to the torques generated and the last ones have reported the infl uence of this profi le in the heat transfer and the pressure drop. However, no advances have been recently published about the microalgae cultivation in a FBRT, which are focused on the collector curvature where the critical area is located and the infl uence of uncommon geometries is considered for the solar collector (square, hexagonal and octagonal) in the agitation of the cultivation.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic computational evaluation in solar tubular photobioreactors bends with different cross section

Ramírez-Duque

Ramos-Lucumi

2011

CT&F Cienc. Tecnol. Futuro

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In this article, the hydrodynamic behavior of a single-phase flow in various solar collectors with different cross sections (circular, octagonal, hexagonal and square), with same hydraulic diameter and longitudinal profile was analyzed. Secondary flow, pressure drop and shear stress were evaluated, because the photosynthetic efficiency and microalgae endurance depend on these properties. These parameters were reviewed at six different culture inlet rates in the collector (from 0,25 to 0,5m/s), emphasizing in the bends regions. A higher speed and agitation was present in the square solar collector, contrary to what happened to the circular one. Despite this, the circular solar collector remains the best option for the industrial implementation phase. However, the shear stress generated in the culture -as it passes through the 180° bend of the solar collector- affects the microalgae growth, as stated in the literature.

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Heat transfer and pressure drop in hexagonal ducts with surface dimples

Cited by 43 publications

References 25 publications

Heat Transfer of Oil/MWCNT Nanofluid Jet Injection Inside a Rectangular Microchannel

Heat Transfer of Oil/MWCNT Nanofluid Jet Injection Inside a Rectangular Microchannel

Optimization of Dimples in Microchannel Heat Sink with Impinging Jets—Part B: the Influences of Dimple Height and Arrangement

Hydrodynamic computational evaluation in solar tubular photobioreactors bends with different cross section

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